Traditionally a radio Studio to Transmitter Link (STL) system encodes program content at a studio site and transports this content wirelessly over a FCC licensed frequency to a far-end transmitter site. This wireless radio link is unidirectional. A typical application is for a commercial radio station whose main transmitter tower is located away from the studio or content production site. This radio station can use a radio STL system to transport program content. In the United States, the FCC provides a licensed radio band between 944 and 960 MHz specifically for this purpose (FCC part 74, Subpart E—Aural Broadcast Auxiliary Stations). Depending on the locations to be connected, a station may choose either a point to point (PTP) link on another special radio frequency, or a newer all-digital wired link via a dedicated T1 or E1 (or larger-capacity) line. Radio links can also be digital, analog, or a hybrid of the two. Even on older all-analog systems, multiple audio and data channels can be sent using subcarriers. As with any communication system, primary link degradation or failure can occur due to equipment failure or environmental conditions.